1. Volume 16, Issue 22, Pages 2259-2264 (November 2006)
Role of CLASP2 in Microtubule Stabilization and the Regulation of Persistent Motility 
Ksenija Drabek, Marco van Ham, Tatiana Stepanova, Katharina Draegestein, Remco van Horssen, Carmen Laura Sayas, Anna Akhmanova, Timo ten Hagen, Ron Smits, Riccardo Fodde, Frank Grosveld, Niels Galjart 
Current Biology 
Volume 16, Issue 22, Pages (November 2006)
DOI: /j.cub
Copyright © 2006 Elsevier Ltd Terms and Conditions

2. Figure 1
CLASP2 Regulates MT Stabilization and Persistent Motility in Fibroblasts
(A) Targeting of the murine Clasp2 gene. A GFP-lox-neo-lox cassette was inserted into a common exon used by all-known CLASP2 mRNA splice variants (common exon 2). The neo gene is transcribed antisense with respect to the Clasp2 gene. Length of 5′-end and 3′-end homologous arms is indicated. RI stands for EcoRI restriction enzyme site; TK stands for thymidine kinase negative-selection marker. LoxP sites are indicated by triangles.
(B) Western-blot analysis. Protein extracts of two wild-type (lines 1 and 8) and two CLASP2-deficient (lines 2 and 6) MEF lines were incubated on western blots with antibodies against CLASP2 (#2358) and β-tubulin.
(C) Levels of acetylated MTs. Wild-type and Clasp2 knockout MEFs were fixed 4 hr after migration into a wound. Cells were incubated with antibodies against acetylated tubulin, a marker for stable MTs. An arrow (20 μm) indicates the direction of cell migration.
(D) Comparison of acetylated and total MTs. Fluorescent intensities of acetylated tubulin and β-tubulin stainings were quantified for wild-type and Clasp2 knockout MEFs 4 hr after migration into a wound. More than 50 cells were measured from each genotype and for each staining. SEM is indicated.
(E) Cold-resistant MTs in motile MEFs. After cold-treatment, wild-type and Clasp2 knockout MEFs were fixed and stained with antibodies against β-tubulin.
(F) Nocodazole-resistant MTs in motile MEFs. After treatment with 10 μM nocodazole, wild-type and Clasp2 knockout MEFs were fixed and stained with antibodies against β-tubulin. The scale bar represents 10 μm.
(G and H) Cell-motility assay. Total and directionally persistent migration distance were measured in wild-type (line 8) and Clasp2 knockout (line 6) MEFs. The directionally persistent migration (D/T) is the ratio of direct distance from start to end point (D), divided by the total track distance (T). Of each genotype, 30 cells were measured (SEM is indicated); each individual track is shown in (G).
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3. Figure 2 MT Network in APC1638T MEFs
(A–F) Immunofluorescence analysis. Wild-type (A, C, and E) and APC1638T (B, D, and F) MEFs were examined 4 hr after migration (toward the right) into a wound. Antibodies against tyrosinated tubulin (A and B), acetylated tubulin (C and D), and EB3 (E and F) were used. The scale bar in (A) represents 7.5 μm, in (E), 2.5 μm.
(G) Comparison of stable and total MTs. Fluorescence intensities of acetylated tubulin and β-tubulin were quantified for two wild-type and two APC1638T MEF lines 4 hr after migration into a wound. More than 50 cells were measured from each genotype and for each staining. SEM is indicated.
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4. Figure 3 ACF7 Regulates CLASP2 Localization in HeLa Cells
(A–C) HeLa cells, transfected with a scramble siRNA oligo, were fixed 3 days after transfection and stained for CLASP2 (green in merge) and ACF7 (red in merge). CLASP2 and ACF7 accumulate at the cell cortex. Note that there is not a complete colocalization.
(D–I) HeLa cells were fixed 3 days after transfection with different siRNAs against ACF7 and stained for CLASP2 (green in merge) and ACF7 (red in merge). Cells depleted of ACF7 (indicated by asterisks) show reduced CLASP2 signal at the cell cortex. MT-end staining of CLASP2 (indicated by arrows in merges) is not affected.
(J–L) HeLa cells, transfected with siRNAs against CLASP1 and CLASP2, were fixed 3 days after transfection and stained for CLASP1 and CLASP2 (green in merge) and ACF7 (red in merge). Cells depleted of CLASPs (indicated by asterisks) still show ACF7 staining at the cell cortex. Scale bars in (A) and (D) represent 10 μm, in (G) and (J), 7.5 μm, and in (C), (F), (I), and (L), 3 μm.
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5. Figure 4 GFP-CLASP2 Behavior in Cultured Cells
(A–C) FRAP analysis in transfected HeLa cells. GFP-CLASP2 localizes at the ends of growing MTs (arrows) and accumulates at the cell cortex. In (A), a still image of a high-resolution time-lapse experiment (Movie S1) is shown. Transfected cells were bleached in the cell body (internal, n = 9) and at the cell cortex (edge, n = 11). Average fluorescence recoveries are shown in (B). In (C), fluorescence recovery at the edge in untreated cells is compared to cells treated with 100 nM wortmannin (n = 8). In (B) and (C), time (s) is on the horizontal axis, and relative fluoresence (normalized to 1) is on the vertical axis. The scale bar in (A) represents 2.5 μm.
(D–F) FRAP analysis in nonmotile 3T3 cells. GFP-CLASP2-positive accumulations were bleached (region of interest, or ROI, 1). Fluorescence intensities were measured in ROIs 1–4. In (F), the average fluorescence recovery is shown from accumulations measured in different cells (n = 16, untreated cells; n = 10, nocodazole-treated cells). In (E) and (F), time (s) is on the horizontal axis and relative fluoresence ([E], expressed as percentage; [F], normalized to 1) on the vertical axis. The scale bar in (D) represents 1.5 μm.
(G–I) GFP-CLASP2 behavior in migrating 3T3 cells. (G) and (H) show migrating cells 30 and 90 min after serum induction, respectively. The arrow in (G) (30 μm) indicates direction of migration. The complete time-lapse analysis is shown in Movies S4 and S5. The asterisk indicates the nucleus of a migrating cell. White round dots represent a stationary circle, within which fluorescence intensity of GFP-CLASP2 was measured during the time-lapse analysis. This intensity is depicted in (I), where the arrows indicate the 30 and 90 min time points. A.U. stands for arbitrary units.
(J–L) FRAP analysis in migrating fibroblasts. Cells were bleached (ROI 1, stippled rectangle in [K]), and fluorescence intensities were measured in the indicated ROIs. In (J) and (K), selected still images are shown. The arrow in (J) (5 μm) indicates direction of cell migration. The complete time-lapse analysis is shown in Movie S7. In (L), fluorescence intensities are plotted with time (s) on the horizontal axis and with relative fluoresence (percentage) on the vertical axis.
Current Biology  , DOI: ( /j.cub )
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